Doctors are encouraging women not to be alarmed by a new study linking the use of hormone replacement therapy (HRT) with a slightly increased risk of Alzheimer’s disease.

The Royal College of GPs says the research does not prove that HRT causes Alzheimer’s disease and that women who are using the therapy should continue to do so.

The study, which was recently published in the BMJ, assessed data available for 170,000 post-menopausal women over 14 years. The scientists compared women who had received a diagnosis of Alzheimer’s with age-matched controls who had not received a diagnosis.

The researchers identified a 9 to 17% increased risk for the disease among women taking HRT, particularly those who took the treatment for more than ten years.

This translates as between nine and 18 additional cases of Alzheimer’s per year for every 10,000 women aged 70 to 80 years.

It should be noted that the study was observational and did not actually prove that HRT causes Alzheimer’s, and the scientists could not exclude the possibility of other factors such as diabetes or cardiovascular disease influencing the results. In fact, other research has demonstrated that HRT can improve brain function.

The GPs are reassuring women that HRT is a safe and effective therapy for most individuals with menopause symptoms and that any risk of Alzheimer’s developing is “extremely low.”

Chairwoman of the college, Helen Stokes-Lampard, says the therapy can be of excellent benefit to many women who suffer from unpleasant side-effects of the menopause such as hot flushes and night sweats. There is also a large body of evidence demonstrating the safety and effectiveness of the therapy.

However, there are risks associated with the use of any medication and it is important that women are made aware of them, she warns:

Alzheimer’s charities have also called the research inconclusive and advised women not to be put off taking HRT for a short period.

Chief scientific officer for Alzheimer’s Research UK, Dr. David Reynolds, said that anyone concerned about the effects of the treatment should speak to their doctor.